This project focuses on the human Y chromosome in the context of the Human Genome Project. The principal long-term goal of this project is complete definition of the genetic content of the human Y chromosome. Toward that end, overlapping recombinant DNA clones spanning the chromosome will be isolated, and these clones together with landmarks based in the DNA sequence itself will be used to construct a high- resolution physical map of the chromosome. This physical map should provide a foundation for future efforts to determine the DNA sequence of the Y chromosome in its entirety. In parallel, a second map of the chromosome will be constructed using naturally occurring deletions of the Y chromosome as found in human individuals. The resulting information will provide a framework for elucidating the function of the Y chromosome in medically relevant processes as diverse as spermatogenesis, tumorigenesis, and embryonic development.